Professor Stapledon, the doyen of Australian engineering geology, has for at least the past three decades been advocating a carefully considered approach to site investigations. For example, Stapledon (1983) says that he believes that the geotechnical investigation should include some of the following geo-aspects which we have quoted:
Stapledon (1982), on dams (he notes that he was inspired by a similar suggestion by Peck,(1962), suggested that desirable attributes for those wishing to contribute to sub-surface engineering should include:
His accompanying recommendations for study of world and regional geological settings are reproduced here as Table 1.1. He introduces this table by saying that in order to determine a "semi-quantitative model (engineering-geological)", geological studies "should commence with consideration of the site location with respect to global tectonics, and include studies of the geology of a broad region surrounding the site. The main objectives and suggested activities for work on a regional scale are set out in [Table 1.1]. " He goes on to say, "The regional geological studies should be followed by studies on intermediate and detailed scales, a principal purpose of which is to ensure that the site geology "fits" into the regional geological picture, i.e. that the country adjacent to or containing the site is in situ, not displaced by major landslide or fault movements." [Our bold for emphasis]
We recommend the adoption of this first wise dictum, of starting with a broad regional understanding. However, this approach does not appear to be widely recommended. For example, the Australian Standard 1726 (1993), on Geotechnical Site Investigations, Item 4.7, says the process of evaluating the geotechnical character of a site "may include ... evaluation of the geology and hydrogeology of the site". It is silent on the construction of a geological model and on the understanding of regional geology and processes. The British Standard on Site Investigations, BS5930 (1981) has a somewhat similar silence. Even Peck's (1969) list quoted above, which starts with item (a) on 'Exploration', might be construed as starting without a desk study of the local and regional geology and his item (b) says only, 'In this assessment geology often plays a major rôle'.
We believe that in general the use of engineering geologists and geomorphologists and the application of intuitive and knowledge-based approaches which characterise good engineering geology do not occur at a level of involvement in projects that is commensurate with the worth of their contribution. In the authors' experience, it is not uncommon for engineering geologists to become involved after problems have developed rather than before.
failings relate to poor investigation technique and lack of geological understanding or assessment. Regrettably, the message from such studies often either falls on the ears of the converted or simply fails to reach the point of impact with the designers and those who award investigation contracts.